*{
    margin: 0;padding: 0;
    list-style: none;
}
#title{
    width: 100%;
    height: 50px;
    background-color: pink;
    line-height: 50px;
    text-align: center;
}
#head{
    width: 100%;
    height: 50px;
    
}
#head>li{
    display: inline-block;
    width: 30%;height: 40px;
    line-height: 40px;
    text-align: center;
}
.on{
    background-color: plum;
}